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HY the medieval alchemist should have plagued himself more with the task of converting base metals into gold rather than with the equally fascinating problem of making gems from ignoble material perhaps some scholar versed in the mysterious ways of the Rosicrucians and of those who sought the Philosopher's Stone can explain. Curiously enough, only the modern chemist has attempted to produce precious stones which lapidaries and jewelers will accept as genuine. For which reason the annals of the diamond and the pigeon-blood ruby contain no records of cryptic phrases mumbled in secret chambers at midnight over seething vessels, nor of necromantic passes with magic wands over misshapen retorts. Before he ever attempted to mimic nature the chemist first determined what is the exact composition of the few stones that are worth manufacturing. Without that knowledge he could hardly hope to construct a gem that nature herself might mistake for her own product.

Nothing could be simpler or sounder in principle, yet nothing more difficult of accomplishment. Ages after the fire has been extinguished, what do we know of the temperature of a planetary melting-pot, the contents of which were stirred and intermingled

by terrific volcanic explosions? What do we know of the pressures that caused a priceless crystal to separate from a solution that boiled eons ago in some huge basin that is now a ruby mine in Burma or a diamond field in South Africa? The materials of which rocks are composed can be discovered easily enough; but obviously the processes that formed a living world, and incidentally studded that world with gems, cannot always be inferred with absolute accuracy. Yet, overwhelming in scope and in complication as the whole subject is, the scientist has grappled it with astonishing success.

The work that has been done in producing the diamond in the laboratory typifies the research methods that underlie the manufacture of all gems. For over a hundred and fifty years chemists have known that there is no chemical difference between charcoal and the finest stones that ever came out of Kimberley, that the diamond is but crystallized carbon, and that the whole problem of making a diamond in a factory is simply a matter of finding a way of crystallizing charcoal. The Kohinoor that blazes in the diadem of a potentate, the black rod of graphite lodged in the middle of your lead pencil, and the charcoal obtained from the burning of wood are all variant

forms of carbon, just as ice is but another form of water. It seems so childishly simple to change one form into the other that the great chemist Liebig once wrote to his friend and colleague Woehler: "Soon I will send you a diamond as thick as your thumb." That was in 1839. Yet only in our own day was the secret of crystallizing carbon, of making real diamonds, discovered.

Perhaps Liebig wrote so confidently because it is no difficult matter to crystallize many elements. A shapeless mass of sulphur, for example, can be converted into beautiful yellow crystals by heating it in a crucible until it melts and allowing the molten mass to cool. On the walls of the crucible fine crystals are deposited by the vapors of sulphur rising from the molten mass. Unfortunately, charcoal is not so readily crystallized into diamonds because, when it is heated under ordinary conditions, it does not melt and form a liquid but flashes immediately into gas. For all that, the diamonds of nature were probably formed from liquid carbon; how was ascertained only after years of study and experimenting.

Sometimes an element may be crystallized from its solutions. Common table salt can be dissolved in water, but only in limited amounts. When the limit is reached, no more salt can be taken up. Heat the water, however, and you will find that a little more can be dissolved. When the solution cools, the excess salt, dissolved because the water was heated, is deposited in the form of crystals. A somewhat similar method has been tried with carbon. Molten iron will dissolve carbon, and the amount dissolved is governed largely by the temperature of the iron. When the iron is cooled, we expect to obtain crystals of carbon. We do. They are not the dazzling transparent crystals that we know as diamonds, but the black crystals that we call graphite.

To the late Professor Henri Moissan, a brilliant French chemist, we owe what we know of the artificial production of diamonds. Like every modern scientist, he began his work in the most sensible, the most logical way imaginable-by studying the diamonds of nature and the mode of their occurrence.

He analyzed diamonds carefully. To do that he had to burn them. That expensive proceeding was by no means novel. Moissan repeated it simply to confirm the analyses of his predecessors. All of them had said that in the ash of a burned diamond traces of

iron could be detected. He, too, found that an infinitesimal amount 'of iron is contained in the purest stones. He learned that wherever a diamond is unearthed quartz is sure to ber discovered near it, and quartz, Moissan knew, is formed only by great pressure. He also knew that molten iron had the property of dissolving carbon. Hence iron and great pressure were in some way necessary for the making of diamonds. These were his only scientific clues to a puzzle that had mystified chemists for over one hundred and fifty years. Possibly, he concluded-possibly, natural diamonds had crystallized under great pressure from a solution of carbon in molten iron.

Before he wasted time and energy in further experimenting he studied the literature of diamonds. He learned that a mineralogist of note, Dr. E. A. Foote, had actually discovered minute diamonds in the fragment of a meteorite picked up in Arizona. Foote's fragment was a chip of what is known as the Cañon Diablo meteorite. Some thousands of years ago—perhaps it was even tens of thousands of years ago—a blazing meteor had struck Arizona. In a crater-like formation, three-quarters of a mile in diameter and about six hundred feet deep, the earth still bears the scar of that encounter. The meteor, a huge mass of molten iron whirling through space, was scooped up, as it were, by the irresistible attraction of the earth. Like most meteors, it must have exploded soon after it entered the earth's atmosphere; for pieces of it, varying in weight from a fraction of an ounce to half a ton, are scattered over an area five miles in diameter. Ten tons of this meteoric iron have thus far been collected for the museums of the world. Dr. Foote proceeded to cut his specimen in two. His tools were ruined by something harder than mere iron-something which, upon chemical analysis, proved to be tiny diamonds, both black and transparent. Moissan immediately procured a specimen of the Cañon Diablo meteorite. He made an independent examination and verified all that Dr. Foote had stated.

Molten iron is like water in this respect. When it chills and solidifies, it expands. That pipes often burst when water within them freezes every one knows who has ever paid a plumber's bill. The molten iron of which the Cañon Diablo meteorite is composed had chilled until a hard crust had been formed with an intensely hot liquid interior. As the

liquid interior froze it expanded, and the outer crust resisted that expansion. An enormous pressure was created-just what was needed to crystallize the carbon from the iron and to form diamonds. Thus Moissan explained the presence of diamonds in the meteorite of Cañon Diablo.

The next step was the creation of an artificial, miniature meteorite, something in which intense heat and terrific pressure could be generated. Moissan built himself an electric furnace. It was very simple. A block of limestone and two electrodes connected with a dynamo-that was all of which it was composed. The limestone block was hollowed out to receive a crucible. In the crucible

Moissan packed a mixture of pure iron and carbon made by burning sugar. When the powerful current was turned on-so powerful that every working minute cost Moissan one dollar-the crucible and its contents were raised to a temperature of over seven thousand degrees Fahrenheit. The sun is not much hotter. The iron became like hot, liquid wax and dissolved the sugar carbon. After a few minutes the limestone of the furnace itself began to melt and the iron to float off in clouds of vapor-so fierce was the heat. His eyes shielded by colored glasses, Moissan seized a pair of tongs and lifted the blinding white crucible-his miniature meteorite and dropped it into ice-cold water.

Exactly what happened thousands of years ago when the Cañon Diablo meteorite collided with the earth was repeated on a small scale, except that there was no explosion. A skin of chilled iron was formed that resisted the effort of the still liquid interior to expand. In that tremendous pressure diamonds were formed-not Kohinoors, but microscopic crystals, the biggest of which was only one thirty-second of an inch in diameter, and therefore too small for any practical purpose. Each microscopic diamond cost him. about five times as much as a natural diamond of equal size; but a great geological secret had been revealed, something that was well worth the price paid in intellectual effort and in money. Moissan repeated the experiment many times in after years. Never was he able to obtain a diamond that a jeweler would dignify by calling it even a chip. Nor have

others been more successful.

If we judge Moissan's results merely by the size of his diamonds, his achievement must seem as ridiculous as that of a circus clown who succeeds, after frantic efforts, in evoking a barely audible squeak from a gigantic megaphone. Yet scientific men consider Moissan's discoveries epoch-making. A Gradgrind may ask, "What is the use of spending years of time and thousands in money to produce a diamond that can be seen only with a magnifying-glass?" The answer is that, thanks to Moissan, the diamond is no longer a perennial puzzle, one of the "riddles of the painful earth," as a great poet once expressed it. We know exactly how nature's diamonds were produced, and what forces are essential to make them artificially in a factory. Moissan worked with high temperatures, but with comparatively small pressures. If we are to make a

salable diamond, we must have far more powerful mechanism at our disposal than Moissan was able to command. Some day that mechanism will be provided, and the diamond factory of Niagara Falls will compete with the Premier Mine of South Africa.

That Moissan was right has been proved by others who sought to obtain great pressures and great heat in ways different from that which he employed. A few years ago Sir Andrew Noble, one of the greatest living authorities on explosives, detonated some cordite in closed cylinders of steel. A pressure of over fifty tons to the square inch and a temperature of over ninety-seven hundred degrees Fahrenheit were attained. Work

ing with specially prepared explosives containing an excess of carbon, Sir Andrew collected the residue left in the cylinders and gave it to Sir William Crookes for analysis. Sir William found that true minute diamonds had been formed.

It must not be forgotten that nature made her diamonds with a great heat, applied, not for a few minutes, but for centuries, and perhaps for thousands of years; with a quantity of carbon measured, not by ounces, but perhaps by tons; and with pressures far exceeding those obtained by Sir Andrew Noble, and exercised, not for the fleeting fraction of a second during an explosion, but for protracted intervals of time. Perhaps the chemist will never succeed in making a Cullinan—a stone that weighed a pound and three-quarters in the rough-but some day he will elaborate Noble's simple apparatus and produce stones that the jeweler will not disdain to set in a necklace.

If Moissan himself never made a fortune out of his discovery, a French swindler named Lemoine did. No less a person than Sir Julius Wernher, a prominent officer of the South African diamond syndicate, fell a ready prey to Lemoine-proof, perhaps, that the owners of diamond mines do not view with equanimity the discovery of a commercial process for manufacturing Kohinoors. After having examined stones that Lemoine claimed had been produced by his secret process, Sir Julius Wernher advanced large sums for the building of a factory. No diamonds were forthcoming. Lemoine was arrested and brought to trial.

Experts identi

fied the gems that he had displayed to Sir Julius as diamonds bought from known sources. Sir Julius had pinned his faith on the statements contained in a certain sealed envelope that had been locked by Lemoine in a safe. On the day appointed for the opening of the envelope in court, the day which was to decide whether or not a historic swindle had been perpetrated, Lemoine wisely disappeared. In the court records the "secret" process, rather too literally translated from the French by some court clerk, is thus revealed:

I, the undersigned, Henri Lemoine, declare that to make artificial diamonds it is sufficient to employ the following process: (1) Take a furnace; (2) take some powdered sugar carbon; (3) place the carbon in a crucible; (4) place the crucible in the furnace and raise the temperature to from 1,700 degrees C. to 1,800 degrees C. in order to obtain crystallization; (5) when this